Solar absorber fence system

ABSTRACT

A fence system whereby the fence pickets are hollow and made of clear material such as plastic or glass. The pickets are constructed to act as solar absorbers and warm air convects up the pickets to a top rail where the air is conveyed to a space to be heated. Cold air in shaded pickets is restrained from entering the top rail by means of baffles or heat exchanger.

BACKGROUND OF THE INVENTION

The invention related to solar heat absorber assemblies, and solarabsorber assemblies which may also be used as a fence. In addition, theinvention relates to low cost solar absorber assemblies that aretolerant to partial shading.

Most current solar absorbers seek to maximize heat absorbed per unitarea. Two techniques are generally employed to do this: location andinsulation. The technique of locating the solar absorber where it israrely shaded and where its angle to the sun is nearly optimal, almostalways results in the roof being selected as a mounting location. Thedrawbacks of the roof are that it is an expensive place for mounting,and that it is a difficult place to perform maintenance. In addition,most absorbers are well insulated so that the maximum amount of heat isabsorbed. However, this does not necessarily result in the highestbenefit/cost ratio.

Solar absorber fence systems have previously been disclosed for swimmingpools. These systems use pool water as the heat transfer fluid, which isnot appropriate for winter heating applications as it will freeze. Inaddition, these systems do not have any provisions for minimizing heatloss in parts that are shaded.

SUMMARY

The present invention aims to provide a low cost solar absorber system.

When used as a fence where a fence would be purchased if the presentinvention were not available, the cost of the space heat benefit fromthe present invention is only the incremental cost above the cost of afence. In order to minimize the incremental cost, the system can be madeof un-insulated plastic or glass. However, the shaded and cold part ofthe system must be isolated from the hot parts of the system in ordernot impair the function of the hot parts of the system. This isaccomplished by not conveying air through the solar absorbers butallowing it to rise by natural convection. Hot absorbers will be cooledby circulating cooler air through a hollow top rail which will removethe heat at the top of the absorber and allow the absorber to continueto collect heat without overheating or losing an unreasonable amount ofheat to the ambient air. Absorbers that are shaded may have a smallsection at the top that is heated by hot air moving through the toprail, but the cold air lower in the absorber will stay there as it ismore dense than the hot air at the top.

The design incorporates features that reduce the tendency of hot air toflow from the top rail into a shaded and cold absorber, which wouldreduce the effectiveness of the un-shaded areas.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 shows a section of fence.

FIGS. 2, 3, and 4 shows cross sections of different designs for a solarabsorber assembly.

FIG. 5 shows a section view of the bottom rail, absorber, and top rail.

FIGS. 6, 7, 8 and 9 show section views of the top rail and the topportion of a solar absorber.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a portion of a fence panel 10 is shown according tothe present invention. It is supported by conventional posts 11 of wood,plastic, or steel set in concrete or dirt. The bottom rail 12 functionsto support the solar absorbers 14 and to act as a mounting point toattach the fence panel 10 to the posts 11 with straps or brackets 13.The upper rail 15 also acts to support the solar absorbers 14 and act asa mounting point to attach the fence panel 10 to the posts 11 withstraps or brackets 13. In addition, the upper rail 15 acts as a ductthrough which warm air can flow and be carried into a space where heatis desired. Upper rail 15 may also act as a solar absorber.

Solar energy can be absorbed in the collector via many differentmethods. FIG. 2, section A-A, shows a preferred embodiment where anabsorber 14 is formed from plastic or glass 20 and coated on the insidewith an absorber coating 21. The coating 21 must fully coat the portionof the absorber 14 that is opposite the sun (back) and may also coat thepart of the absorber 14 that is closest to the sun (front). Coating theentire absorber 14, or not protecting and masking the part of theabsorber 14 that is closest to the sun during the coating process mayhave manufacturing cost advantages.

Referring to FIG. 3, also section A-A, the absorber 14 can be made of aclear plastic or glass 20 and contain a solar absorber plate 30.Absorber plate 30 may be attached to the back of the absorber 14 usingadhesive or mechanical fasteners. Plate 30 can be mounted such that anair gap exists between the back of the absorber 14 and the plate 30. Theair gap may result in improved convection of hot air.

Referring to FIG. 4, also section A-A, the front of absorber 14 can bemade of a clear plastic or glass 20, while the back 40 is made of darkopaque solar absorber material such as textured black plastic. The back40 is shown un-insulated but may contain an insulation layer.

FIG. 5 shows a vertical cross section (B-B) of the lower rail 12, thesolar absorber 14, and the upper rail 15. Because some absorbers 14 ofthe fence panel 10 may be shaded and cold, it is not desirable to moveair through these sections. Therefore, lower rail 12 does not have aninternal opening to allow air to flow from it and into solar absorber14. Instead, warm air is naturally convected up solar absorber 14 andinto upper rail 15 where it is moved to the space to be heated via ablower. When a portion or all of solar absorber 14 is shaded the airinside it is not heated and does not rise into upper rail 15.

Currents flowing through upper rail 15 may disturb the air in a coldsolar collector 14 and cause some of the cold air to be conveyed withthe warm air in top rail 15. This is not desirable since it willdecrease the temperature of the air and reduce the ability of the entiresystem to heat a space. FIGS. 6, 7, 8 and 9 (section C-C) illustratemethods to reduce or eliminate this mixing effect. In FIG. 6, a baffle18 is used inside the solar absorber 14 to reduce the amount of mixing.In FIG. 7, a baffle 17 is used inside the top rail 15 to reduce theamount of mixing. In FIG. 8, a constriction 23 is placed in the solarabsorber 14 to reduce unintended air flow. Referring to FIG. 9, abarrier 32 is placed between the top rail 15 and solar absorber 14 toprevent the mixing of cold air from the absorber 14 into the top rail15. In order for heat to be conducted from warm absorbers into the toprail, heat exchange fins 31, which may be made from thin aluminum,extend from inside the solar absorber 14, through the barrier 30, andinto the top rail 15.

1. A fence system that has a second, either primary or secondary,purpose as a solar heat absorber system comprising: Solar heat absorbersthat allow heat to flow to a space to be heated, and rely on convectionto convey heated air into a top rail instead of blowing air through theabsorbers via a bottom rail.
 2. The system of claim 1 whereby the solarabsorbers allow air to flow directly into a top rail, and the air flowis directed with a baffle either in the absorber tube or in the top railand/or a constriction in the absorber tube.
 3. The system of claim 1whereby the air flow from the solar absorbers to the top rail is blockedand heat is conducted to the top rail via a heat exchanger.